检索结果-南通市图书馆

Chinese Science Bulletin 2008年第3期53卷 426-433页

作者： WANG XunMing LI JiJun DONG GuangRong xia dunsheng Key Laboratory of Desert and Desertification Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences Lanzhou 730000 China School of Resources and Environment Lanzhou University Lanzhou 730000 China

There have been significant variations in wind activity over the past five decades in arid and semiarid areas in *** wind activity occurred from the 1960s to the 1970s,but wind activity has de-creased continuously from the 1980s to the present;as a result,the potential sand transport during the latter period was only 20%-50% of the values during the 1960s and *** of high wind activ-ity were highly consistent with the trends in desertification over the past five decades in arid and semiarid areas in China,but spring precipitation was also a significant factor:rapid desertification during the 1960s and 1970s was due to high wind activity,generally combining with low spring pre-cipitation;subsequent rehabilitation since the 1980s has resulted from the combined effects of low wind activity and higher spring ***,although modern desertification and rehabili-tation processes are being more or less affected by human activities,both processes appear to be more strongly controlled by climate change.

关键词：中国干旱半干旱地区土壤荒漠化风向

Fluvial sediments in the Alagxa Plateau as a dust source: iron mineralogical and geochemical evidence

在线全文

学校读者我要写书评

暂无评论

Journal of Arid Land 2019年第2期11卷 217-227页

作者： WANG Youjun JIA Jia LU Hao LU Caichen xia dunsheng College of Tourism and Environmental Resource Zaozhuang University College of Geography and Environmental Sciences Zhejiang Normal University College of Earth and Environmental Sciences Lanzhou University

The Alagxa Plateau, in the margin of the northeastern Tibetan Plateau, is one of the most important dust source areas in East Asia, and the widespread sandy desert in the area is important both as a reservoir and a source of eolian silty. The northeastern margin of the Tibetan Plateau is one of the most actively-growing mountain belt on earth, and has large amounts of debris, with masses of fine grained material, which were continuously mobilized and deposited in the Alagxa Plateau by rivers, forming broad alluvial fans. It is possible that the role of fluvial sediments as a source of silty dust in the Alagxa Plateau has been underestimated. In this study, we test this hypothesis by investigating the iron mineralogical and geochemical characteristics of the fluvial sediments and the surface material of the sandy desert in the Alagxa Plateau, and comparing them with paleo-eolian dust deposits(loess) in the adjacent Chinese Loess Plateau(CLP) to investigate the possible linkages among the fluvial sediments, sandy desert and the last glacial loess of the CLP. The results show that sandy desert typically have high contents of goethite, and high ratios of goethite to hematite, similar to the fluvial sediments in the Alagxa Plateau. Based on the major element characteristics, field investigations and the results of previous studies, we found a genetic link between the silt component of the fluvial sediments and the sandy desert in the Alagxa Plateau with high value of Gt(goethite) and similarity of the Gt/(Hm(hematite)+Gt) ratio. But the silt component of the sandy desert main come from the adjacent fluvial sediments. The iron mineralogical characteristics(χ(magnetic susceptibility), χARM(anhysteretic susceptibility), SIRM(saturation isothermal remanent magnetization) and SIRM_(AF100 mT)(SIRM demagnetized at 100 mT)) of the CLP samples overlap with those of the fluvial sediments in the Alagxa Plateau, but there is a mismatch with the sandy desert samples. This suggests th

关键词： fluvial sediments silty dust sandy dust iron mineralogical and geochemical characteristic Alagxa Plateau

Rapid oscillations of Chinese monsoon climate since the last deglaciation and its comparison with GISP2 record

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 1999年第3期44卷 284-285页

作者： Jianmin Wang Qi Shi Fahu Chen dunsheng xia Lanzhou Univ Dept Geog Lanzhou 730000 Peoples R China

The geographic extent of the climate oscillations during the last deglaciation is an open question in the world. Here a high resolution climate record from a 16 000 C-14 a loess sequence in the northwestern margin of the Chinese Loess Plateau is reported. Comparison with GISP2 record shows that all major climate oscillation(e. g. Oldest Dryas/ Bolling/ Older Dryas/Allerod/Younger Dryas) in the North Atlantic region also registered in the record. In addition, the sequence also contains some other distinctive strengthened winter monsoon periods. It is suggested that a coupling mechanism operate between the two areas, and climate oscillations in the North Atlantic region may not be a local phenomenon.

关键词： last deglaciation loess record monsoon cliamte.

Magnetic property of loess strata recorded by Kansu profile in Tianshan Mountains

在线全文

学校读者我要写书评

暂无评论

Journal of Arid Land 2011年第3期3卷 191-198页

作者： Jia JIA xianBin LIU dunsheng xia HaiTao WEI Bo WANG Key Laboratory of West China＇s Environmental Systems （Ministry of Education） College of Earth Sciences and Environments Lanzhou University Lanzhou 730000 China Key Laboratory of Desert and Desertification Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences Lanzhou 730000 China

Kansu （KS） profile is located in the east of Yili basin, western Xinjiang, where typical loess sediments are distributed. The magnetic parameters （such as IRM, SIRM SOFT, and M） and grain size in the KS profile were analyzed in the study. The results showed that the magnetic property of KS loess is dominated by ferrimagnetic minerals, such as magnetite and maghemite. Antiferromagnetic and superparamagnetic minerals also exist in the profile, but had less impact on magnetic susceptibility. Compared with the typical loess sediments of the central Loess Plateau in China, the strata of Kansu profile contained more magnetic minerals and hard magnetic minerals. The analysis of grain size for magnetic minerals indicated that the properties of loess and paleosol were respectively dominated by PSD/MD and coarse SSD magnetite. The research found that the contents of magnetic minerals in loess and paleosol sequences in Kansu profile were similar, but the proportion of fine grained magnetite and soft magnetic minerals were varying, which implies a positive relationship between the value of magnetic susceptibility and intensity of pedogenesis.

关键词： loess sediment magnetic properties pedogenesis Kansu profile Tianshan Mountains

Magnetic records of heavy metal pollution in urban topsoil in Lanzhou,China

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2013年第3期58卷 384-395页

作者： WANG Bo xia dunsheng YU Ye JIA Jia XU ShuJing Key Laboratory of West China's Environmental Systems(Ministry of Education) Lanzhou University Key Laboratory of Desert and Desertification Cold and Arid Regions Environmental and Engineering Research InstituteChinese Academy of Sciences

This study is a systematic analysis of the magnetic characteristics and heavy metal elements in soil samples collected from Lanzhou City,*** 117 surface soil samples were measured to study the feasibility and effectiveness of environmental magnetism for evaluating heavy metal pollution in urban *** of the study indicate that low-coercivity magnetite dominates the magnetic properties in the *** high values of the soil magnetic mineral concentration parameters and low values of magnetic particle size parameters are distributed throughout the northern area of Xigu District,the industrial zones of the eastern section of Chengguan District and the districts of the narrow sections connecting Chengguan District and the other three districts;these parameters are fundamentally consistent with the distribution of the high values of the Pollution Load Index and Nemerow Pollution ***-quantitative studies which use the environmental magnetic method to monitor pollution of heavy metals(such as As,Cr,Cu,Ni,Pb,Zn,and Fe) have shown that when xlf≤35×10-8 m 3 kg-1,it is unpolluted;when 35≤xlf <150×10-8 m3 kg-1,it is moderately polluted to unpolluted;when 150≤xlf <365×10-8 m 3 kg-1,it is moderately polluted;when 365≤xlf <750×10-8 m3 kg-1,fd %<2.7 and ARM /SIRM<0.2×10-3m A-1,it is moderately to highly polluted;when xlf ≥750×10-8 m3 kg-1,xfd %<2.7 and xARM/SIRM<0.2×10-3m A-1,it is highly *** region of moderately to highly polluted distribution is caused by industry and vehicles,showing that the change of pollution in Lanzhou City bears the trend of "vehicle emission + industrial".

关键词：土壤重金属污染城市表层土壤环境磁学兰州市中国土壤样品污染指数污染负荷

Humid Medieval Warm Period recorded by magnetic characteristics of sediments from Gonghai Lake, Shanxi, North China

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2011年第23期56卷 2464-2474页

作者： LIU JianBao CHEN FaHu CHEN JianHui xia dunsheng XU QingHai WANG ZongLi LI YueCong Key Laboratory of Western China's Environmental System (Ministry of Education) Lanzhou University Lanzhou 730000 China College of Resources and Environment Hebei Normal University Shijiazhuang 0500161 China

Variations in monsoon strength, moisture or precipitation in eastern China during the MWP reflected by different climatic records have shown apparent discrepancies. Here, detailed environmental magnetic investigations and mineralogical analyses were conducted on lacustrine sediments of Core GH09B1 (2.8 m long) from Gonghai Lake, Shanxi, North China, concerning the monsoon history during the MWP. The results demonstrate that the main magnetic mineral is magnetite. The sediments with relatively high magnetic mineral concentrations were characterized by relatively fine magnetic grain sizes, which were formed in a period of relatively strong pedogenesis and high precipitation. In contrast, the sediments with low magnetic mineral concentrations reflected an opposite process. The variations of magnetic parameters in Gonghai Lake sediments were mainly controlled by the degree of pedogenesis in the lake drainage basin, which further indicated the strength of the Asian summer monsoon. The variations in the and S 300 parameters of the core clearly reveal the Asian summer monsoon history over the last 1200 years in the study area, suggesting generally abundant precipitation and a strong summer monsoon during the Medieval Warm Period (MWP, AD 910–1220), which is supported by pollen evidence. Furthermore, this 3–6-year resolution environmental magnetic record indicates a dry event around AD 980–1050, interrupting the generally humid MWP. The summer monsoon evolution over the last millennium recorded by magnetic parameters in sediments from Gonghai Lake correlates well with historical documentation (North China) and speleothem oxygen isotopes (Wanxiang Cave), as well as precipitation modeling results (extratropical East Asia), which all indicate a generally humid MWP within which centennial-scale moisture variability existed. It is thus demonstrated that environmental magnetic parameters could be used as an effective proxy for monsoon climate variations in high-resolution lacustr

关键词：湖泊沉积物中世纪暖期磁性矿物中国北方潮湿特征记录山西季风强度

Spatial and temporal variation in magnetic properties of street dust in Lanzhou City,China

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2008年第12期53卷 1913-1923页

作者： WANG Guan xia dunsheng LIU XiuMing CHEN FaHu YU Ye YANG LiPing CHEN JianHui ZHOU AiFeng Key Laboratory of the West Environmental System Lanzhou University Lanzhou 730000 China Key Laboratory of Desert and Desertification Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences Lanzhou 730000China

Urban environmental problems are of increasing concern. Lanzhou is a large industrial city in North-west China. Street dust samples representing different temporal and spatial scales were collected for magnetic properties study. Magnetic measurements indicate a high concentration of magnetic minerals in Lanzhou street dust, dominated by pseudo-single domain (PSD) magnetite. The concentration of magnetic materials is distinctly high in winter and spring, low in autumn. Similarly, higher concentra-tions associated with heavy industry, concentrated residential development, and vehicular traffic sug-gest mixed contributions of magnetic material from both anthropogenic and natural sources. χ_lf and SOFT% are effective magnetic parameters that denote seasonal differences among magnetic proper-ties in street dust, convenient and economical methods for monitoring street dust pollution.

关键词：磁性街道尘埃城市污染兰州市

Linking moisture and near-surface wind with winter temperature to reveal the Holocene climate evolution in arid Xinjiang region of China

在线全文

学校读者我要写书评

暂无评论

Geoscience Frontiers 2022年第6期13卷 16-29页

作者： Fuyuan Gao Junhuai Yang dunsheng xia Hao Lu Shuyuan Wang Kaiming Li Zhenqian Wang Zhipeng Wu Jiaxin Zhou Fuxi Shi College of Urban Environment Lanzhou City UniversityLanzhou 730070China Key Laboratory of Western China’s Environmental Systems(Ministry of Education) College of Earth and Environmental SciencesLanzhou UniversityLanzhou 730000China Key Laboratory of Cenozoic Geology and Environment Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China Georges Lemaitre Center for Earth and Climate Research Earth and Life InstituteUniersitéCatholique de LouvainLouvain-la-Neuve 1348Belgium Key Laboratory of State Forestry and Grassland Administration on Forest Ecosystem Protection and Restoration of Poyang Lake Watershed College of ForestryJiangxi Agricultural UniversityNanchang 330045China Yulong Snow Mountain Cryosphere and Sustainable Development Field Science Observation and Research Station Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China

An increasing number of palaeo-climatic records have been reported to identify the Holocene climate history in the arid Xinjiang region of northwest China. However, few studies have fully considered the internal linkages within the regional climate system, which may limit our understanding of the forcing mechanisms of Holocene climate change in this region. Here, we systematically consider three major issues of the moisture/precipitation, temperature and near-surface wind relevant to the Holocene climate history of Xinjiang. First, despite there still has debated for the Holocene moisture evolution in this region, more climatic reconstructions from lake sediments, loess, sand-dunes and peats support a long-term regional wetting trend. Second, temperature records from ice cores, peats and stalagmites demonstrate a long-term winter warming trend during the Holocene in middle-to high-latitudes of Asia. Third, recent studies of aeolian sedimentary sequences reveal that the near-surface winds in winter gradually weakened during the Holocene, whereas the winter mid-latitude Westerlies strengthened in the Tienshan Mountains. Based on this evidence, in the arid Xinjiang region we propose an early to middle Holocene relatively cold and dry interval, with strong near-surface winds;and a warmer, wetter interval with weaker near-surface winds in the middle to late Holocene during winter. Additionally,we develop a conceptual model to explain the pattern of Holocene climate changes in this *** the early to the late Holocene, the increasing atmospheric COcontent and winter insolation,and the shrinking of high-latitude continental ice-sheets, resulted in increasing winter temperatures in middle to high latitudes in the Northern Hemisphere. Subsequently, the increased winter temperature strengthened the winter mid-latitude Westerlies and weakened the Siberian high-pressure system,which caused an increase in winter precipitation and a decrease in near-surface wind strength. T

关键词： Holocene climate change Moisture Temperature Near-surface wind strength Siberian high-pressure system Mid-latitude Westerlies

Near-surface wind environment in the Yarlung Zangbo River basin,southern Tibetan Plateau

在线全文

学校读者我要写书评

暂无评论

Journal of Arid Land 2020年第6期12卷 917-936页

作者： YANG Junhuai xia dunsheng WANG Shuyuan TIAN Weidong MA Xingyue CHEN Zixuan GAO Fuyuan LING Zhiyong DONG Zhibao Key Laboratory of Western China's Environmental Systems(Ministry of Education) College of Earth and Environmental SciencesLanzhou UniversityLanzhou 730000China College of Geography and Environmental Engineering Lanzhou City UniversityLanzhou 730070China Key Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resources Qinghai Institute of Salt LakesChinese Academy of SciencesXining 810008China School of Geography and Tourism Shaanxi Normal UniversityXi'an 710119China

Aeolian processes have been studied extensively at low elevations,but have been relatively little studied at high *** sediments are widely distributed in the Yarlung Zangbo River basin,southern Tibetan Plateau,which is characterized by low pressure and low ***,we comprehensively analyzed the wind regime using data since 1980 from 11 meteorological stations in the study area,and examined the interaction between the near-surface wind and aeolian *** wind environment exhibited significant spatial and temporal variation,and mean wind speed has generally decreased on both annual and seasonal bases since 1980,at an average of 0.181 m/(s•10a).This decrease resulted from the reduced contribution of maximum wind speed,and depended strongly on variations of the frequency of sand-driving *** drift potential and related parameters also showed obvious spatial and temporal variation,with similar driving forces for the wind *** strength of the wind regime affected the formation and development of the aeolian geomorphological pattern,but with variation caused by local topography and sediment *** drift potential and resultant drift direction were two key parameters,as they quantify the dynamic conditions and depositional orientation of the aeolian *** affected the spatial variation in sediment grain size,but the source material and complex topographic effects on the near-surface wind were the underlying causes for the grain size distribution of aeolian *** results will support efforts to control aeolian desertification in the basin and improve our understanding of aeolian processes in high-elevation environments.

关键词： wind regime sand dune aeolian activity Yarlung Zangbo River Tibetan Plateau

Holocene dust storm variations over northern China:transition from a natural forcing to an anthropogenic forcing

在线全文

学校读者我要写书评

暂无评论

Science Bulletin 2021年第24期66卷 2516-2527,M0004页

作者： Shengqian Chen Jianbao Liu Xin Wang Shuang Zhao Jianhui Chen Mingrui Qiang Bing Liu Qinghai Xu dunsheng xia Fahu Chen Key Laboratory of Western China’s Environmental Systems(Ministry of Education) College of Earth and Environmental ScienceLanzhou UniversityLanzhou 730000China Group of Alpine Paleoecology and Human Adaptation State Key Laboratory of Tibetan Plateau Earth SystemResources and EnvironmentInstitute of Tibetan Plateau ResearchChinese Academy of SciencesBeijing 100101China Center for Excellence in Tibetan Plateau Earth Sciences Chinese Academy of SciencesBeijing 100101China College of Geography and Tourism Qufu Normal UniversityRizhao 276826China School of Geography South China Normal UniversityGuangzhou 510631China Key Laboratory of Desert and Desertification Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China College of Resources and Environment Hebei Normal UniversityShijiazhuang 050024China

Asian dust storms have long been a major environmental concern in China,affecting the lives of about one billion ***,it is unclear whether the mechanisms responsible for Asian dust storms during the Holocene varied on different timescales,and thus it is unclear whether there was a shift from a natural forcing to an anthropogenic forcing of dust *** reconstructed a high-resolution Holocene record of dust storms from the sediments of an undisturbed alpine lake on the Chinese Loess *** found that Asian dust storm activity generally increased during the Holocene,with the largest fluctuations occurring during the past 2000 *** increase in dust storm activity was in contrast to the decrease in East Asian winter monsoon(EAWM)intensity during the Holocene,indicating that the EAWM played a limited role in modulating dust *** contrast,the increase in dust storms corresponded to a decrease in East Asian summer monsoon(EASM)*** demonstrates that EASM precipitation was the dominant control of dust storm activity on a millennial timescale,because decreased EASM precipitation expanded the desert area and thus increased the dust storm *** increasing intensity of human activity in the region since the Bronze Age resulted in an acceleration of dust storm activity against the background of decreased EASM *** human disturbance continued to intensify,beginning at least at~2 cal ka BP,increased dust storms were closely linked to increasing human populations in the dust source regions,and there is a strong temporal coherence between increased dust storms and higher EASM *** was completely different from when natural processes are *** that period,fewer dust storms occurred during periods of a strengthened ***,there was a shift from a natural forcing to an anthropogenic forcing of dust storms on a multi-decadal to centennial timescale,and was a mode in which‘‘human activity overtoo

关键词： Asian dust storms Early anthropogenic hypothesis East Asian summer monsoon Human activity Northern China